Prior to the precision working of tooth flanks of pretoothed spur gears by shaving, rolling or similar methods, there generally occurs a control over the workpiece so as to maintain the prescribed dimensions, in particular the tooth-width dimension. Otherwise, if deviations in the measurements exist, it is possible for the precision machining tool to be destroyed. On assembly lines, where the machines are connected to suitable conveying devices which move the workpieces independently into the operating chamber of the machine and remove same again after the respective machining operation, this control requires a relatively high input of supply, chucking and drive devices for the measuring station.
Therefore, the basic purpose of the invention is to combine the measuring device with an operation which occurs prior to the finish working of the tooth flank. This purpose is inventively attained by changing or supplementing a conventional apparatus for the cutting, deburring or breaking of the side tooth edges so that it can also be used as a measuring device. Such an apparatus is described in German AS No. 23 19 060 and U.S. Pat. No. 4,068,558, in which gearlike tools are provided on axially facing sides of the workpiece, the teeth of which are provided with cutting edges and which are fixedly connected against rotation with a guide gear which is arranged between them and which meshingly engages the workpiece. When the guide gear is designed wider than the tooth system of the workpiece, then it can be constructed as a measuring gear. For breaking or deburring the side tooth edges of the workpiece, the apparatus, after meshing interengagement is established, is moved in axial direction first to the one and then to the other side until the cutting edges have produced the desired edge break or chamfer on the workpiece teeth. With this the advantage is simultaneously achieved that the center adjustment of the apparatus must not occur so exactly as in the known apparatus, where both front sides of a workpiece are machined simultaneously. A further advantage is to be seen in that for similar workpieces with different tooth width the same tool can be used. This of course is also true for apparatus of the described type, in which the guide gear is not constructed as a measuring gear, for which reason the invention is also directed to this.
A guide gear which is constructed as a measuring gear can be moved into engagement prior to the actual operation of deburring or edge breaking until a backlash does no longer exist. The thereby existing distance between the axes is measured independently at a low speed and is compared with a pregiven desired value.
If the desired value is exceeded or does not reach a certain value, the machine is switched off and the measurement result is indicated. The respective workpiece can then either be reworked or it becomes scrap. If the given desired value is maintained, then the guide gear and the workpiece are moved away from one another until a small amount of backlash exists. The deburring or edge breaking occurs then at a higher speed, by moving the apparatus as already described in the axial direction.
Through the burr which exists on the pretoothed workpieces, it can easily happen that the measurement result is erroneous, namely, when the flanks of the workpiece do not directly rest on the flanks of the measuring gear, but rest on the burrs which exist on the side edges. The flanks of the guide or measuring gear are, therefore, advantageously provided with recesses which extend from the tooth addendum to the tooth dedendum at each of two locations which are spaced from one another approximately at the distance of the tooth width of the workpiece to be machined. These recesses can be formed by grooves which extend in direction of the tooth height or by slots which divide the teeth into three side-by-side lying sections. The burrs which exist on the workpiece extend then into the recesses in the flanks, where they do not contact the flanks themselves. It is thusly assured that the workpiece flanks correctly rest on the flanks of the measuring gear and a satisfactory measurement result is achieved.